Hydrofluorocarbon (HFC) products are widely utilized in many applications, including refrigeration, air conditioning, foam expansion, and as propellants for aerosol products including medical aerosol devices. Although HFC's have proven to be more climate friendly than the chlorofluorocarbon and hydrochlorofluorocarbon products that they replaced, it has now been discovered that they exhibit an appreciable global warming potential (GWP).
The search for more acceptable alternatives to current fluorocarbon products has led to the emergence of hydrofluoroolefin (HFO) products. Relative to their predecessors, HFOs are expected to exert less impact on the atmosphere in the form of a lesser or no detrimental impact on the ozone layer and their much lower GWP as compared to HFC's. Advantageously, HFO's also exhibit low flammability and low toxicity.
As the environmental, and thus, economic importance of HFO's has developed, so has the demand for precursors utilized in their production. Many desirable HFO compounds, e.g., such as 2,3,3,3-tetrafluoroprop-1-ene or 1,3,3,3-tetrafluoroprop-1-ene, may typically be produced utilizing feedstocks of chlorocarbons or chlorofluorocarbons, and in particular, chlorinated propenes.
Unfortunately, many chlorinated propenes may have limited commercial availability, and/or may only be available at potentially prohibitively high cost, due at least in part to the propensity of the conventional processes typically utilized in their manufacture to result in the production of large quantities of secondary products, i.e., waste and/or by-products. Any such secondary products produced not only have to be separated from the final product and disposed of, but also, can result in system fouling prior to doing so. Both of these outcomes can introduce substantial expense, further limiting the commercial potential of processes in which the production of such secondary products is not reduced or eliminated. Further, these problems become exacerbated on process scale-up, so that large scale processes can become cost prohibitive quickly.
In many conventional processes for the production of chlorinated propenes, formation of excessive secondary products can be difficult to avoid since many such processes require only partial conversion of the limiting reagents. Greater conversions can result in the production of large quantities of secondary products. Excessive conversion, in turn, can be caused by backmixing of reactants and/or products.
Various mixers have been developed in efforts to minimize backmixing of reactants that may occur prior to entry into the reactor; however, none of these are without detriment. For example, mixers have been provided having the same diameter as the reactor so that backmixing zones are not created at the junction there between. When coupled with appropriate introduction of reactants, these mixers have proven effective, but can yet be suboptimal.
First, building a mixer with the same large diameter, e.g., up to 8 feet, as many reactors for the production of chlorinated propenes can be costly. Furthermore, the use of large diameter mixers can make the desired flow distribution within the mixer difficult to obtain due to the drop in pressure and velocity of the reactants upon entry into the mixer from their respective feed lines.
It would thus be desirable to provide improved mixers for use in methods wherein limiting reactants are desirably utilized. More particularly, mixers that provide quick and thorough mixing of two or more reactants, while yet also minimizing back mixing of the mixed feed stream and thus providing a reduction in the amount of secondary products that are produced would be welcomed in the art. Further advantage would be seen if such mixers could be provided cost effectively, i.e., on a smaller scale than the reactors with which they are desirably utilized.